The present invention relates to a method for providing a lining of a ceramic material to a hollow body by means of a thermit reaction or, more particularly, to a method for providing a ceramic lining to a hollow body by means of a thermit reaction taking place under the influence of a centrifugal force.
The invention also relates to a metal hollow body provided with a ceramic lining layer formed by the above method.
It is a conventional practice that various kinds of pipes and vessels of metals used for transportation of fluids or handling of chemical substances in carrying out chemical reactions are provided with a lining of a ceramic material in order to improve their resistance against corrosion, abrasion and heat.
There have been proposed several methods for providing such a ceramic lining to a hollow body of a metal including coating methods and binding methods. In the coating method, the inward surface of the hollow body is coated with a ceramic material followed, if necessary, by baking. In the binding method, on the other hand, another hollow body of a ceramic material is shaped in advance with somewhat smaller dimensions than the metal hollow body and the ceramic body is inserted into the metal body followed by filling the narrow interstices therebetween with a melt of a low-melting metal.
The former coating method is limited in the thickness of the ceramic lining layer so that it is not applicable when a ceramic lining of relatively large thickness is desired. The latter method of insertion is defective, even if setting aside the problems caused by the multiplicity of the fabrication steps, in that the adhesion between the ceramic insert and the metal shell is not always complete. Therefore, the ceramic layer frequently comes off the metal wall by repeated thermal expansion and contraction or by a mechanical shock.
Thus, none of the prior art methods is satisfactory for providing a ceramic lining with sufficient thickness to a metal hollow body without the danger of peeling or exfoliation even by a large heat shock or mechanical shock.